It is the 2nd anniversary game in the series and as such shares more similarities to "Puyo Puyo! 15th Anniversary" than "Puyo Puyo 7". This game came out 4 months before "Sonic Generations", which is also commemorating the 20th anniversary of the Sonic games.
There are 24 playable characters available, each with their own 8-stage course (similar to Puyo Puyo! 15th Anniversary).
This game, as it's predecessor, was released only in Japan.
It was a usual day for our protagonist, Ringo Andou. Her friend Maguro Sasaki visited Ringo and Risukuma's clubroom. Risukuma was conducting an experiment with a boiling flask, but it goes wrong, and the three were blown to another dimension...
FantasyComedy
Game modes: Single player, Multiplayer, Split screen
Quick answers
When was Puyo Puyo!! 20th Anniversary released?
Puyo Puyo!! 20th Anniversary released on December 15, 2011, developed by Sonic Team and published by Sega.
What platforms is Puyo Puyo!! 20th Anniversary available on?
Puyo Puyo!! 20th Anniversary is available on Nintendo 3DS, Wii, PlayStation Portable, Nintendo DS. It supports single player, multiplayer, split screen.